Operant acuity of toddlers and developmentally delayed children with low vision.

The present report describes an operant procedure for the assessment of grating acuity in young and/or developmentally delayed children. Prior to testing, the child was trained to point to a grating presented on one of two equally bright screens. A reward was given to the child for each correct response. During the test, the gratings became progressively finer until the child no longer made consistently correct choices. Normative data from 90 children show improvement in grating acuity during years one to five (from 20/50 to 20/17). Results were also obtained from 100 consecutive pediatric patients who were thought to be visually unresponsive or visually impaired by the referring ophthalmologist. Overall, 12% of these children tested within the normal range, 53% had grating acuities better than 20/200 but below normal, 27% had acuities below 20/200, and 8% were not measurable. These results suggest that a wide range of visual potential exists in this population and that some of these children may benefit from visual aids and training.